ECONOMIC ASSESSMENT OF INNOVATIVE PROCESSES FOR BIOMETHANE PRODUCTION

Two innovative carbon dioxide removal methods from biogas, characterized by the capture of the removed carbon dioxide by accelerated carbonation, were proposed and investigated. According to the first investigated method, the carbon dioxide is removed from the biogas by alkali solution absorption, which is at least in part regenerated through reaction with calcium contained in the Air Pollution Control residues, from waste incineration, capturing the carbon dioxide. The second method is based on direct carbon dioxide adsorption on bottom ash, by means of gas/solid direct contact process. A technical feasibility assessment of the two methods was carried out, based on pilot plant operation results, highlighting some constraints on the possibility of operating at very large scale, due to the high amount of required residues. Then a preliminary economic assessment of the two methods was carried out, with the aim of estimating the specific cost of treatment on appropriate industrial scale and compare it with the costs of commercial methods. The economic assessment results are reported in the paper.